Quick and easy clamping device

ABSTRACT

A quick-tying device, preferably, combines objects that are to be tied together, especially, combines hair to form braids, ponytails or the like. The quick-tying device includes a flexible tightening device which can be shaped into a loop, and a stop element which is adjustable along the free ends of the tightening device. The tightening device is shaped into two loops, both of which equally embrace the material to be tied together; and a single stop element has a plurality of openings for threading the tightening device therethrough.

The invention refers to a quick clamping device, preferably for the holding of objects to be fixed to each other, in particular for the holding of hair to ponytails, pigtails etc. This is accomplished with a traction means forming at least one loop, and an adjustable stop holder through which the free ends of the traction means are drawn.

A type-appropriate quick clamping device is known from the German utility model 71 33 699. This reveals a holder for hair to ponytails, pigtails etc. and shows the hair contained in an elastic band forming a loop as well as a hold body providing tension with an opening by which both ends of the loop-shaped elastic band are led and are fixed in it with friction.

The disadvantage is that the elastic band within its opening cannot be fixed permanently with friction because this constantly slips through. For the same reason no raised tensions within the elastic band can be built up; as soon as the tension becomes bigger, the slide or slip movement increases, until the tension has reduced again on a moderate value. If the opening within the hold body was further narrowed, the elastic band can be threaded on the one hand only with difficulty, and, on the other hand, deliberate, active loosening is just as difficult.

From the disadvantages of the described state of the art, the problem initiating the invention results to improve a quick clamping device, especially a self-tightening hair band, in such way that the traction means can be drawn quickly and simply around the objects to be fixed to each other and shall not bear any slip, but shall remain permanently tensioned. Removal of the device at a later time should be as easy as the insertion.

The solution of this problem succeeds by the fact that the traction means is formed into two loops, and the stop element has several openings through which the traction means is threaded.

As traction means, long-stretched, pliable elements come to consideration such as cords, bands, shoelaces. Especially preferred are traction means which are not only flexible, but also elastic, such as rubber bands. The traction means according to the present invention has two ends and is not closed ring-shaped in itself.

For the following calculations a form of a circle should be assumed for the cross section of the traction means with a cross section area A=π*r² and r is the radius of the elastic band explains in each respective state. The length l of the traction means can also change as a function of the tension state.

Furthermore the volume V of a traction means, the length l and the cross section radius r is given to V=l*π*r². In the case of a tension state σ in longitudinal direction of the traction means, the traction means length changes from l₀ in the relaxed state to l₁ in the tense state. On the other hand, the volume remains largely steady: V=const., must be valid:

$\begin{matrix} {V = {{I_{0} \star \Pi \star r_{0}^{2}} = {I_{1} \star \Pi \star r_{1}^{2}}}} \\ {= {{I_{0} \star A_{0}} = {I_{1} \star {A_{1}.}}}} \end{matrix}$

From that follows, that

A ₁ =A ₀ *l ₀ /l ₁.

The cross section area A is conversely proportional to the current length l. The Hooke's law is valid for the length l of the elastic traction means:

F=D*Δl=D*(l ₁ −l ₀)

or:

l ₁=(F/D)+l₀,

with the spring constant D.

The tractive power F is in turn a measure of the tension state σ in longitudinal direction of the traction means; the following formula applies:

σ=F/A=D*l ₁*(l ₁ −l ₀)/(A ₀ *l ₀)=(l ₁ ² −l ₁ *l ₀)*D/(A ₀ *l ₀)

One recognizes from this formula that the tension σ in longitudinal direction of the traction means is approximately proportional to l₁ ², and because of the above equation, l₁=(F/D)+l₀ is also approximately proportional to F².

This means that with increasing tractive power F in longitudinal direction of the traction means, in this cross section in a pulled state of tension, σ in longitudinal direction rises as a square function of the tractive power F.

Therefore, the first means for the reduction of the tension σ within the traction means consists of the forming this into two loops, which both encircle the hair or the other objects to be fixed with each other. The tractive power F within each loop can be thereby halved while the same hold strength can be maintained because the hold strength of each loop is added. The tension G can be thereby reduced to about one quarter compared with an instep tape with only one loop and the same hold strength or tractive power F. Therefore by far higher hold forces can be generated, without danger of the snatch of the draw.

Furthermore, the tractive powers compensate for themselves in the crossing between both loops, so that no other measures are necessary for the fixation. Merely each free end of the traction means must be held by the holder under tension. Nevertheless, the tension σ is reduced to about one quarter compared with customary hair bands and other recognized holders thanks to the second loop. Beyond that, the holder shows two openings for which each end of the traction means can be drawn through. The opening cross section can be thereby adapted optimally to the cross section of the traction means; in particular the possibility exists to calculate the cross section of the opening a little smaller than the cross section of a single rope of the traction means in its relaxed state. Since the free ends beyond the opening are completely relaxed, they will be generally thicker, especially with an elastic band.

From V=l*A=l*π*r²=const. follows for the dimensions l₀, r₀ in the relaxed state and the dimensions l₁, r₁ in the tense state:

l ₀ /l ₁ =r ₁ ² /r ₀ ²

or:

r ₁ ² /r ₀ ² =l ₀ /l ₁

From that follows Δl=l₁−l₀ by solving for l₁ as well as under use of Hooke's law: l₁=l₀+Δl=l₀+F/D an easy formula for r₁. Used this delivers:

r ₁ =r ₀ *[l ₀/(l ₀ +F/D)]^(1/2).

With a tension σ=0 follows accordingly the preliminary calculations F=0, and hence, the above formula delivers for the relaxed state again r₁=r₀.

The relaxed end of the traction means can widen behind the hole and spreads itself therefore against the inside edge of the hole and gets jammed there. An inadvertent slipping through the hole is virtually excluded.

If the tension σ>0 then it follows that F>0, and from the formula above r₁<r₀. That means the radius r of the traction means decreases and at some point the traction means starts to slide through the related hole, namely when the tractive power F becomes bigger than the frictional strength R. Therefore:

F≦R.

This limit is reached at the latest when r₁≦r_(h), where r_(h) is the radius of the hole to draw the traction means through one time.

If, nevertheless, a cross section r_(q) of the traction means is bigger than r_(h), the threaded state of the traction means requires an elastic distortion of the traction means for the difference Δr=r_(q)−r_(h).

Also in this case Hooke's law is valid. From it follows:

Δr=N/D or N=Δr*D

The traction means on the inside of the opening exerting a normal strength N which causes again a frictional force R=μ*N according to the frictional value μ. This frictional force R corresponds to the maximum tractive power within the traction means which can be stabilized by the stop element.

The maximum value which one can use for r_(q) is r₀, the thickest area of the traction means in the relaxed state. This originates above all in the area beyond a narrowing of the passageway cross section with the smallest clearance. Behind that area the tension of the traction means reduces until the value F=0. There the strongest frictional force R is generated.

The normal strength N and therefore the frictional strength R are generated in this invention along a line-shaped area, along which Δr=r₀−r_(h)=Δr_(max). This area applies along the internal edge of the concerned opening.

If s is an incremental stretch along this edge, then in a general case Δr could be a function of s: Δr=Δr(s). Then the following is valid: N=N(s)=D*Δr(s).

If the traction means is elastic, it can nestle up to the edge of the opening optimally, so that along the complete periphery an infinitesimal normal strength dN(s) and therefore an infinitesimal frictional strength dR(s)=μ*dN(s)=μ*D*dΔr(s) is generated. The total frictional strength R results by integration along the periphery line:

R=μ*D*∫Δr(s)ds=μ*D*∫[r _(q)(s)−r _(h)(s)]ds

With this invention rq(s)=rq=const. as well as r_(h)(s)=r_(h)=const. and therefore also Δr(s)=r_(q)−r_(h)=const is valid thanks to the circular cross sections of the traction means and the end-sided hole. The integration simplifies itself to

R=μ*D*(r _(q) −r _(h))*U=μ*D*(r _(q) −r _(h))*2π*r _(h).

This is concurrently also the maximum tractive power F within the traction means which can be stabilized by the frictional strength R.

Therefore, with the invention the complete edge of the hole contributes to the frictional strength R.

With the previously mentioned existing design according to the DE 71 33 699 U, this area is by far shorter because both ends of the traction means are threaded together through one single hole. The traction means also has generally a round cross section and a hole by the process of the drilling. Therefore each traction means end lies at best only on half of the edge of the hole; though the remaining extent of a traction means rope is also compressed in the ideal case; nevertheless, from it no hold strength can result because the segment adjoining to it is just the other rope which itself threatens to slip out from the hole and therefore cannot take up axial force. Additionally, the infinitesimal hold strength ΔF cannot be achieved because a real traction means does not have the cross section of a semicircle and therefore the available space is not utilized. Practically only about one quarter of the available area can actually be used. Hence, with the existing design, valid is approximately:

R=μ*D*(r _(q) −r _(h))*¼*U=μ*D*(r _(q) −r _(h))*½*π*r _(h).

Therefore, the controllable tractive power F within the traction means with this invention is at least fourfold that of the existing design.

A further advantage is that even if a rope end slips, the other respective rope end is not affected. One thereby has, so to speak, a redundancy which provides that the bunch of hair or other objects cannot loosen. By contrast the existing design according to DE 71 33 699 U, both rope ends are led together through the same hole and are hence connected frictionally with each other. Hence, in that case both rope ends slip out of the opening together.

It has shown to be favorable that the area between the loops of the traction means is led through the holder at least once.

It is advantageous for the purpose of this invention that at least when under tension, the elastic traction means ropes are not directly in line with the holes in the holder. Additionally, the friction μ between the traction means and the inside edge of the hole should be as much as possible.

The invention intends furthermore that in the area between the two loops and or in the middle area where the traction means goes through the holder, the traction means runs somewhat parallel to the shape of the holder. The traction means under tension in this area, similar to the ends, is at a strong angle to the holes in the holder. Therewith, as mentioned above, the virtual, elliptical deformation provides for substantial normal strength N and frictional strength R.

Another advantage arises from the fact that the traction means is led through the holder at least three or four times. This bigger number of threading leads to a smooth connection of both parts with each other, and therefore quite substantially reduces the danger of slipping.

Accordingly this invention shows at least one continuous middle opening in the holder for the realization of the middle area between both loops of the traction means. There the middle area of the traction means is connected with the holder and is fixed in it frictionally. With the existing design, DE 71 33 699 U, the middle area of the traction means is neither encompassed by the holder nor fixed frictionally.

Furthermore the holder in this invention shows each side section with one hole for threading of each end of the traction means. These are the holes that hold the traction means under tension with substantial frictional strength.

An advantageous feature of the invention is that two ropes of the draw are never led together through the same hole of the holder.

If only one single rope of the traction means is led through a hole of the holder, the cross section of the hole can be easily adapted to the corresponding cross section of the traction means, in particular if both show circular cross sections. In this invention the full cross section of such a hole is thereby filled completely by the traction means.

It lies within the scope of the invention that the holder is connected with the traction means, but not integrated. A production from different materials is thereby possible. The traction means is adaptable and mainly elastic, while the holder is form-stable and/or hard.

Preferably the holder shows the shape of a long-stretched and/or level or flat body. With it, the holder can be reduced to a geometrical minimum and save material, in particular however, also weight which will improve the comfort level.

The surface of the stop holder can be curved in the area of the middle opening. With it, the holder is enabled to approximately take on the shape of the hair or things being held together and compliment the course of the traction means.

Another design specification says that in the area of a middle opening a footbridge is planned which separates two mouths from each other. Such a bridge can already originate from the fact that two openings lie near each other and the material between them defines the bridge. However, this bridge can also stand out from the surface of the holder, in particular on the side of the holder where the hair is to be bundled together. In this respect a bridge with a bigger cross section can be created as opposed to a bridge defined by two openings through a level part.

Within the scope of the first implementation form there is the previously described bridge within the surface of the holder that separates two middle openings completely from each other. This shows two mouths on each surface of the holder so altogether 4 mouths. Such a design could lend itself to the use of metal which could be stamped and bent.

Another implementation form distinguishes itself by the fact that the bridge is beyond or raised from the surface of the holder and borders the middle opening, so that this shows two mouths on the same side of the surface of the holder.

Preferably the bridge is raised as in the latter described version to the inside of the holder, meaning the side with the traction means loops. By wrapping under this bridge, the course of the traction means can run along the inside of the holder which proves a nearly unchanged curvature of the traction means.

The invention can be made so that the continuous middle opening extends exclusively between the bridge and the body of the holder so that the bridge is not visible from the outside and no hole is visible in the body of the holder from the outside. This can generate among other things an especially elegant aesthetic because the internal functionality of the invention is not discernible in detail from the outside and, moreover, the flat outside would not be interrupted. Therewith, the outside surface could be used for decoration.

Nevertheless, it is also possible that the continuous middle opening does not apply exclusively between the bridge and the body of the holder, but also through the body of the holder, so that the middle opening shows two mouths on the inside and one mouth on the outside. In such a case, the threading of the traction means through the middle opening is perhaps easier. Therewith it can be considered that in the area of such a middle opening, at least regarding the tangential strength component, an equilibrium exists between the two strands or loops. Therefore a clamping or holding of the traction means in this area is not necessary for the function of the device.

The invention intends furthermore that both holes, each of which receives one strand of the traction means, subtend each other diametrically with regard to the middle opening. With it a crossing of the traction means ends is avoided in the area of the holder. Each of the loops wrap the hair or items to be fixed to each other. Each loop does not end at α=360°, but already at an angle of α<360°, for example α≦355°, chiefly α≦350°, in particular α≦345°.

Because the invented quick clamping device shows two loops, the hair or other items to be fixed to each other will be encompassed with a total angle of β=2 α, however smaller than 720°, for example β≦710°, chiefly β≦700°, in particular β≦690°. On the other hand the related angle at the center of the loops is more than β≧540°, for example β≧630°, chiefly β≧660°, in particular β≧675°.

Another characteristic of the invention is that both holes in the side sections are equidistant from the middle opening. This provides a symmetry aspect that may prove advantageous in production as well as more aesthetic.

The layout is further optimized by the fact that both holes and the middle opening lie on a common line. Therefore, with the same tension in both loops, all forces in the sides of the holder are symmetrical and remain balanced in relation with the middle opening as the center.

The holder shows a long shape that runs mainly in parallel with the center line through the three openings. An elegant design can underline the easy effect of the invention aesthetically; moreover, material can thereby be saved, which provides the opportunity to use a higher worth material.

The side sections of the holder which each show one of two holes are level and lie within a common surface. With it the traction means is freed from the need to kink at nearly 90°, as is necessary in the existing design according to DE 71 33 699 U and in that case even welcome to increase the frictional strength. Thanks to the holding force resulting from the invention of the holder, the ends can be designed so as to protect the traction means from constant kinking. Therefore a relatively long term solution is provided for a durable and somewhat higher value jewelry like product.

A curved middle section of the holder can rise above the side sections on the outside starting at a crease or bend. With that the holder has three sections that each contains an opening for the traction means.

The invention recommends the use of an elastic material for the traction means. This can be stretched to a desired tension which in turn provides the desired holding power of the quick clamping device. Moreover, a radial traction means provides the strongest holding power in the invention because it will be radially compressed in the two end holes thus resulting in high contact pressure against the edge of the hole, resulting in a high frictional strength. A radial compressibility may not be synonymous with elasticity but the properties of the latter work in addition for the operation of the invention.

As an additional security the traction means shows at one or both ends a knot. Therewith is an inadvertent entire slipping out of the band eliminated.

Finally, it is advised that as part of the invention, in the area between each of both knots and the holder, a stop element each with a through hole smaller than one knot, are pushed onto the traction means. These would aid in grabbing and holding the ropes when pulling to tighten the quick clamping device. Additionally, this is thought to be a good opportunity to make a more eye pleasing device through the use of decorative stop elements.

Further signs, details, advantages and effects on the base of the invention arise from the following description of a preferential implementation form of the invention as well as with the help of the drawing. Drawing includes:

FIG. 1 an invention-appropriate quick clamping device from the first perspective;

FIG. 2 the quick clamping device shown in FIG. 1 from a second perspective; as well as

FIG. 3 a section view through the quick clamping device shown in FIGS. 1 and 2, partially broken.

The invention appropriate quick clamping device 1 shown in the drawing exists from a total of four parts: one elongated traction means 2, a functionally supplemental holder 3 and two stop elements 4.

The traction means 2 reaches through holes 5, 6, 7 in the holder 3 and in the stop elements 4. While the stop elements 4 are conceivably expendable, the traction means 2 and the holder 3 are essential for the function.

As a traction means 2, a simple, flexible elastic material is used in the shown version. An elastic material is preferred although not just for its elasticity in the longitudinal direction, but also for its elasticity in the crosswise direction. This requirement is fulfilled for example with an elastic band. Less suitable even if imaginable, is in general a spiral tension spring because those are barely able to adjust elastically to the holes 5, 6 and 7 of the holder 3 or the stop elements 4.

The traction means 2 has preferably a circular cross section with a radius r₀ and a length l₀, in each case in the relaxed state of the traction means 2.

From it two loops are later formed. If each of these loops had a circumference of Us=2 πrs, a maximum loop radius r_(s)=l₀/4 π is calculated from it.

Preferably the traction means 2 shows a knot 9 at each of both ends 8.

The holder 3 shown in the drawing can be made of plastic from an injection mold for example. On the other hand, it could also be made from a metallic material.

One can observe that the shape is generally rectangular with a constant thickness. This rectangular form has a pronounced length; for example equal to or more than three times the width, chiefly equal to or more than four times the width, in particular equal to or more than 5 times the width.

This long-stretched rectangle is divided into three segments which line up themselves in a longitudinal direction one after the other: A middle section 10 is flanked by two side sections 11. Currently, both side sections are the same in size and the middle section is larger than the side sections.

Both side parts 11 are mainly level and maintain common surfaces with each other. The middle section 10 however can be curved, namely with a steady curvature radius r_(m)≈r_(s)=l_(z)/4 π.

On account of the steady thickness of the holder 3 the curvature of the middle section 10 has a concave arched inside 12 and a convex arched outside 13.

In each of both side sections 11 is a hole 5, preferred with a circular cross section with a radius of r_(h).

A design regulation to be followed says that the radius r_(h) is smaller than the radius r₀ of the relaxed (unstretched), but also not compressed traction means 2: r_(h)<r₀. This provides a relationship of r_(h)/r₀:r_(h)/r₀<1, possibly r_(h)/r₀<0.9, for example r_(h)/r₀<0.8, chiefly r_(h)/r₀<0.7, in particular r_(h)/r₀<0.6. The traction means 2 is therefore forced to regenerate in the area of its passing through the end holes 5. It does this by summoning an elastic counterforce in an outwardly direction, approximately perpendicular to the edge of the hole 5 which accordingly entails a frictional force.

The middle section 10 also shows a passageway opening 6. This is crossed by a bridge 14 on the inside 12 of the holder 3. This bridge 14 runs crosswise to the length of the holder 3.

The opening 6 extends preferably also into the bridge 14 which results in an arc shape for the bridge 14. The ends of the bridge 14 connect to the inside 12 of the holder 3, specifically above and below the opening 6. As shown in FIG. 3, the cross section of the opening 6 between the bridge 14 and the inside 12 is so large that the traction means 2 can pass through unhindered in the relaxed state.

Both stop elements 4 have mainly a spherical shape, although this is not a requirement because the outside shape is primarily aesthetic. They each have a hole 7 through the center.

Preferentially the cross section of the opening 7 is also circular, with a radius r_(A)<r₀. A recommended ratio is r_(A)/r₀:r_(A)/r₀<1, possibly r_(A)/r₀<0.9, for example r_(A)/r₀<0.8, chiefly r_(A)/r₀<0.7, in particular r_(A)/r₀<0.6.

Through such a small sized radius r_(A), a stop element can be fixed in the desired position on the traction means 2. Should this be directly next to a knot 9, it can act as a counter element stabilizing everything and preventing the knot 9 from opening.

The traction means 2 is threaded before manufacture of the knots 9. This can occur first through the middle opening 6 of the holder 3. Then each of the ends 8 is threaded through the holes 5 in the side sections 11 and through the holes 7 of each stop element. Finally a knot is made close to the end of each of the traction means ends 8. With that the assembly is concluded.

In use, the holder 3 compared with the traction means 2 is pushed first outwardly until the loops 15 have the desired opening size. The loops 15 have approximately the same size as shown in FIG. 2. The maximum loop size is achieved by moving the holder 3 until it rests against the stop elements 4. The bunch of hair or other objects to be held are then fed through the loops 15. Now one needs only to pull the ends 8 probably by gripping the stop elements 4 in addition. This can be done with one hand while the other hand is free to hold the pony tail or other objects in place.

For easiest removal of the quick clamping device 1, one could pinch the holder 3 in the middle and pull down. As one pulls down on the holder, the traction means 2 stretch to create a smaller cross section in the area of the holes 5. This in turn allows the holder to slide down the traction means to create a larger loop size again until it can be comfortably removed.

REFERENCE LIST

-   1 quick clamping device -   2 traction means -   3 holder -   4 stop elements -   5 hole -   6 hole -   7 hole -   8 ends -   9 knots -   10 middle section -   11 side sections -   12 inside -   13 outside -   14 bridge -   15 loops 

1. Quick clamping device for holding of objects to be fixed to each other, comprises one flexible traction device formable into at least one loop, and a stop element adjustable along free ends of the traction, wherein a) the traction device is formed into two loops, which both equally encompass the objects to be fixed to each other; and b) one single stop element with several openings through which the traction device is threaded.
 2. Quick clamping device after claim 1, wherein the area between both loops of the traction device goes through the stop element at least once.
 3. Quick clamping device according to claim 1, wherein the traction device is in the area between both loops, and/or in that area where it is fed through the stop element, is somewhat parallel with the surface area of the stop element.
 4. Quick clamping device according to claim 1, wherein the traction device is fed through the stop element at least three or four times.
 5. Quick clamping device according to claim 1, wherein the stop element comprises at least one continuous middle opening in the middle area between both loops for the traction means.
 6. Quick clamping device according to claim 5, wherein the stop element comprises at least one hole each for the separate threading of both ends of the traction means.
 7. Quick clamping device according to claim 1, wherein two ropes of the traction device are never fed together through the same opening of the stop element.
 8. Quick clamping device according to claim 1, wherein the stop element and the traction device are form-fitting or frictionally connected but not integrated.
 9. Quick clamping device according to claim 1, wherein the stop element has the shape of a plane or flat body.
 10. Quick clamping device according to claim 1, wherein the surface of the stop element is curved in the area of the middle opening.
 11. Quick clamping device according to claim 1, wherein in the area of the stop element or of a middle opening a bridge is provided which separates two mouths from each other.
 12. Quick clamping device according to claim 11, wherein the bridge is arranged within the surface of the stop element and thereby separates two middle openings completely from each other which comprise two mouths on each side of the surface, all together four mouths.
 13. Quick clamping device according to claim 11, wherein the bridge is beyond the surface of the stop element and crosses the middle opening there, so that this middle opening comprises two mouths on the same side of the surface of the stop element.
 14. Quick clamping device according to claim 13, wherein the continuous middle opening extends exclusively between the bridge and the body of the stop element, so that the body of the stop element does not comprise any recess extending to the opposite side facing away from the bridge there.
 15. Quick clamping device according to claim 14, wherein that the passing-through middle opening does not extend exclusively between the bridge and the body of the stop element, but also through the body of the stop element, so that the middle opening shows two mouths on the side facing the bridge, and one mouth on the side facing away from the bridge.
 16. Quick clamping device according to claim 1, both holes are positioned diametrical to each other with regard to the middle opening.
 17. Quick clamping device according to claim 1, wherein both holes are equidistant from the middle opening.
 18. Quick clamping device according to claim 1, wherein both holes and the middle opening lie on a common line, which snuggles to a curved surface of the stop element, otherwise however being straight.
 19. Quick clamping device according to claim 1, wherein the stop element shows a lengthy shape whose longitudinal extension runs in parallel with the center line through the three openings.
 20. Quick clamping device according to claim 1, wherein the end sections of the stop element which each comprise one of the two holes, are plane and lie within a common surface.
 21. Quick clamping device according to claim 1, wherein the curved middle section of the stop element starting at a crease or a curve transforms into the plane end sections aligned with each other.
 22. Quick clamping device according to claim 1, wherein the traction device is an elastic type band.
 23. Quick clamping device according to claim 1, wherein the traction device comprises a knot at one or both ends.
 24. Quick clamping device according to claim 23, wherein in the area between each of both knots and the stop element a stop device each with a through hole preferably with an inner diameter smaller than one knot of the traction device. 